Slice cake into 1/4-inch thick slices. Spread jam on the cake slices and then top with sliced strawberries. Cut cake slices into 1-inch circles and stars and set aside.
Separate the frosting into 3 bowls and add food coloring to reach desired colors (1 to 2 drops of red to make pink, 1 to 2 drops of green to make seafoam and 1 to 2 drops of brown to make cream). Make a glaze by combining the sugar and milk in a medium bowl. Separate the glaze into 3 bowls and tint each to match the frosting colors.
Place cake cut-outs on a wire rack. Fill 3 resealable plastic bags fitted with a star tip with each color of frosting and then pipe desired frosting over. Using a melon baler, add a scoop of ice cream and then sandwich the cut-outs. Drizzle glaze over cut-outs. Let glaze set. Pipe a star on the top of each petit four with the corresponding color of icing. Garnish with a small strawberry slice.